This invention relates generally to fluid current motors and particularly to such motors which are equipped with pairs of moveable rotor panels.
The use of fluid current motors such as windmills and watermills has been well known for centuries. Such motors conventionally include a rotatable shaft and a series of fluid current resisting panels operatively connected to the shaft. These panels are arranged with respect to the shaft such that the impingment of a fluid current will cause a force to build upon the panel surface thereby causing movement of the panel, which movement ultimately results in the rotation of the power shaft, thereby harnessing wind and water power.
As is well known to those skilled in the art, fluid current motors may be divided into two main classes. These are: (a) motors having the effective surfaces of their panels moving in the direction of the wind; and (b) motors whose panels move in a plane, or planes, perpendicular to the direction of the wind. Fluid current motors of the class (a) type suffer from the disadvantage that the panels, which move generally with the wind during one portion of a revolution of the shaft, must move against the wind during an equal portion of a revolution.
Various inventors have attempted to overcome this disadvantage by constructing fluid current motors of the class (a) type which have moveable or pivotable panels which offer less resistance when rotating into the wind than when rotating with the wind.
A fluid current motor having pivotable rotor panels is disclosed in U.S. Pat. No. 346,797 to Aylsworth. The Aylsworth patent discloses a windwheel having a vertical rotatable shaft, four horizontal rotor arms mounted to, and extending radially from, the shaft, each arm carrying a pair of rotor panels individually pivotally mounted to the arm with their individual pivot axes in parallel spaced relation to each other. Each panel has a leading portion terminating in a leading edge and a trailing portion terminating in a trailing edge with the pivotal mounting axis of each panel separating the leading and trailing portions. For the purposes of this disclosure, the term leading is defined to identify the portion of the fluid current rotor arm or panel which is facing in the same peripheral direction as the direction of rotation of the shaft. Conversely the term trailing is defined to identify the portion of the rotor arm or panel which is facing in the opposite direction. In addition, when the panels in a pair of rotor panels are oriented parallel to each other, that particular orientation is termed "non-resisting", whereas, when the panels are oriented with their leading edges closely adjacent and their trailing edges remote, the orientation is termed "resisting".
In operation, impingement of a fluid current on the leading edge of a rotor panel in the Aylsworth device will cause the panel to pivot into a horizontal, or non-resisting, alignment, whereas impingement of a fluid current upon the trailing edge of a panel will cause the panel to pivot into a resisting position in which a portion of one surface of the panel is exposed to the force of the fluid current and in which the leading portion of the rotor panel is forced to rest against the rotor arm.
While the Aylsworth device solves at least a part of the wind resistance problem associated with class (a) fluid current motors by having its rotor panels pivot into a non-resisting orientation when rotating into the wind, the device performs with less than optimum efficiency due to the fact that the independent pivotability of each panel allows the panels to flutter during the rotation cycle. This flutter allows a part of the fluid current to escape respectively over and under the upper and lower trailing edges of the panel pairs and through the opening between the leading edges during the portion of a rotation cycle in which the pairs are in a resisting orientation.
Various inventors have attempted to solve the latter problem, i.e. fluid escape between the leading edges, by constructing rotor panel pairs which are hinged at their leading edges. Examplary of such fluid current motors are those disclosed in U.S. Pat. Nos. 13,268 to Morgan; 244,677 to Sherwood; 257,210 to Casterline; 427,846 to Garcia - Sanchez; 766,801 to Allen; 948,105 to Campbell; and 1,447,686 to Oswald. Fluid current motors constructed with a plurality of such hinged pairs of rotor panels successfully solve the problem of fluid current losses between the rotor panels when in their resisting orientation, fluttering, which allows fluid escape around the trailing edges remains. However, by moving the pivotal axis of the rotor panels to coincide with a hinge axis at the leading edges of the panels, there results an increased tendency for the pairs of panels, to remain in a non-resisting orientation when a fluid current impinges upon their trailing edge. To counteract this tendency several of the aforementioned patentees have added weights, extending outwardly beyond the leading edges of the panels, in order to counter-balance the panel weight and thereby obtain a gravity assisted opening. However, despite such modifications, the drawbacks associated with independent panel motion persist.
One attempted solution to the problem of independent panel motion in fluid current motors having hinged pivotable panels is that shown in U.S. Pat. No. 354,972 to Dodds et al. The Dodds et al patent discloses discrete hinged pairs of rotor panels with the hinged common leading edge being, in turn, mounted to a rotor arm. Each panel is rigidly pivotally connected to a common block which, in turn, is slidably mounted to a slide bar having a terminal stop. In operation, impingement of a fluid current upon the hinged leading edges of a pair of rotor panels will cause the rotor panels to pivot about the hinge into a non-resisting orientation, while impingement of a fluid current upon the trailing edges of the pair will cause the rotor panels to pivot into a resisting orientation. Due to the pivotal connection between each of the panels and the slidable block, the panels will be forced to open and close co-actingly. By virtue of such co-action, the individual panels in each pair exert a stabilizing influence on each other with respect to relative motion.
Despite its attempted solution to the problem of motion between the individual rotor panels of a pair, the Dodds et al device suffers from the disadvantage associated with leading edge hinging, namely a tendency to remain in a non-resisting orientation. In addition the number of interrelated elements necessary to obtain co-action results in substantial maintenance and replacement difficulties.
It is therefore an object of this invention to provide a fluid current motor having discrete pairs of co-actingly pivotable rotor panels which will minimize wind resistance during that portion of a rotation cycle in which the pair is traveling against the fluid current.
It is a further object to provide such a pair of co-actingly pivotable rotor panels which will maximize fluid current resistance during that portion of a rotation cycle in which the pair is traveling with the fluid current.
It is a still further object of this invention to provide such a fluid current motor which will utilize a minumum number of elements to accomplish its function so as to minimize the amount of maintenance and repair operations necessary to maintain operation.